The manufacturing process for fabricating printed circuit boards (PCB) includes steps of multi-layer stacking to stack conducting layers and insulating layers on each other and then pressing to integrate the layers. A common PCB manufacturing procedure is to start from a core substrate, subsequently attach metal conducting layers on both sides of the core substrates by means of stacking, perform pressing and etching on the metal conducting layers to form circuits, stack to attach insulating material on both sides of the core substrate with two circuit layers, and then repeal the aforementioned steps until the outer circuit layer is formed.
After years of technical innovation and improvement, the regular substrates and insulating materials have a form of sheets having a rectangular shape with longitudinal and transverse dimensions of about 20 to 30 inches while the thickness can be only a few millimeters or even less than one millimeter. The sizes of the substrates and insulating materials are about the same. According to traditional stacking methods, the operators need to manually transport and place each sheet of the materials at appropriate locations based on visual inspections and personal experience, which significantly limits the production efficiency and causes deviations in terms of quality. The manual operation for transportation and stacking can no longer satisfy the needs of the industry due to the large amount of market requirements and the rapidly reduced lead time.
Some PCB manufacturers tend to use a method of disposing markers at some specific locations on the materials and taking advantage of visual identification by a computer to establish models of automatic transportation and stacking for production. However, these methods rely on the accuracy of the locations of the markers previously disposed on the surface of the materials, which increase the production cost of the materials on the one hand. On the other hand, errors may occur if any inconsistency or deviation of locations among the markers exists on different batches of the materials made by the vendors. Therefore, there are technical issues to be resolved to avoid the abovementioned problems.